The present invention relates to ribbon cartridges and especially to a cartridge for an endless inked ribbon for a printing mechanism for use with computer terminals and the like.
Prior art ribbon cartridges have the advantage of ease in loading without the attendant hazard of smudging ink on unwanted surfaces, and messy operator handling. The principal disadvantages of available cassettes are inherent complexity resulting in high cost of fabrication and limitations of yardage of inked ribbon relative to available space to accommodate the cartridge. Some prior devices satisfy in part the volume per character printed capability, such as the Parker U.S. Pat. No. 3,918,569, assigned to the assignee of the present invention, which employs a wound bobbin of ribbon which affords a greater length of ribbon within a given space than could be loaded by a "Stuffing box" apparatus, owing to an allowance of space for a packing factor required to avoid creasing or folding of the ribbon. However, the practical reduction of the art taught in the Parker patent is known to require extremely stringent control of the inked coating and winding processes to prevent stressed ribbon from causing early malfunction. These shortcomings were circumvented by the applicant's prior application Ser. No. 622,223, now U.S. Pat. No. 3,993,182, which introduced specific considerations regarding ribbon length, friction and low friction plastics in combination.
In contrast with my prior invention, this invention teaches features which allow a greater tolerance of ribbon conditions while allowing simplicity of fabrication and a reduction of cost. The present ribbon cartridge provides a pre-inked endless ribbon and housing especially suitable for printer mechanisms in computer terminals and point-of-sale devices and the like, accommodating a variety of printer heads including character wheel and wire matrix. The cartridge is adapted to attach easily to a print head and move horizontally with the head as the printer head moves from one horizontal position to another.